/*
 * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
 * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
 */

package org.jetbrains.kotlin.fir.resolve.substitution

import org.jetbrains.kotlin.fir.types.ConeKotlinType
import org.jetbrains.kotlin.fir.types.ConeTypeProjection
import org.jetbrains.kotlin.types.model.TypeSubstitutorMarker

abstract class ConeSubstitutor : TypeSubstitutorMarker {
    open fun substituteOrSelf(type: ConeKotlinType): ConeKotlinType = substituteOrNull(type) ?: type
    abstract fun substituteOrNull(type: ConeKotlinType): ConeKotlinType?
    abstract fun substituteArgument(projection: ConeTypeProjection, index: Int): ConeTypeProjection?

    object Empty : ConeSubstitutor() {
        override fun substituteOrSelf(type: ConeKotlinType): ConeKotlinType {
            return type
        }

        override fun substituteOrNull(type: ConeKotlinType): ConeKotlinType? {
            return null
        }

        override fun substituteArgument(projection: ConeTypeProjection, index: Int): ConeTypeProjection? {
            return null
        }

        override fun toString(): String = "Empty"
    }
}

/**
 * Make a transformation from marker interface to cone-based type
 *
 * In K2 frontend context such a transformation is normally safe,
 * as K1-based types and IR-based types cannot occur here.
 */
@Suppress("NOTHING_TO_INLINE")
inline fun TypeSubstitutorMarker.asCone(): ConeSubstitutor = this as ConeSubstitutor

@Deprecated(message = "This call is redundant, please just drop it", level = DeprecationLevel.ERROR)
fun ConeSubstitutor.asCone(): ConeSubstitutor = this

fun ConeSubstitutor.substituteOrNull(type: ConeKotlinType?): ConeKotlinType? {
    return type?.let { substituteOrNull(it) }
}
